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New Nikon Astro DSLR

JG777

By JG777
in Imaging - Discussion

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griz11

griz11

Posted
Posted

One problem with the Nikon cameras for AP use is they don't use bias on the sensor. Every negative value coming out of the ADU's gets clipped. On the Canon and some of the others the bias is applied which saves this data that is otherwise lost. You get the full histogram with a camera that uses bias. This makes analysis and removal of noise more difficult as it skews the models the software uses to identify and remove the noise.

Griz

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kalasinman

kalasinman

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One problem with the Nikon cameras for AP use is they don't use bias on the sensor. Every negative value coming out of the ADU's gets clipped. On the Canon and some of the others the bias is applied which saves this data that is otherwise lost. You get the full histogram with a camera that uses bias. This makes analysis and removal of noise more difficult as it skews the models the software uses to identify and remove the noise.

Griz

Normally true, but problem has been eliminated by the True Dark current hack by Nikonhacker group.

post-37593-0-51525300-1422864226.jpg

I've been using it for several months. My limited skills and equipment have kept me from realizing the true potential, but it's clearly there. With the low read noise and resulting high dynamic range of the Sony sensor, this is a real advance for AP imagers.

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griz11

griz11

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Don't need to hack anything with the 7D2. ISO's over a certain amount are only multiplied values. Much better to image at lower ISO's that don't just multiply the ADU output by a factor. Kills the headroom for the bright signal reducing the dynamic range. You can do the same thing in post. Is the noise more than 15% lower than the 6Da. If not then the 7D2 has it beat. The 7D2 is 14% quieter and a third of a stop more sensitive than the 6Da. Doesn't really matter and if you already have Nikon stuff I don't advocate selling it off and buying Canon. You can make awesome pictures with any of them but it takes skill. I tried the I'll buy this so my stuff will look better game. Truth is until you can spend thousands on the latest and greatest and your pics might not show it. Are your skills such that you will see if your camera rejects 3 or 4 electrons per well that aren't supposed to be there? Best thing you can do to improve your shots is find yourself some really dark sky. Anything else is an uphill battle. Grab whatever camera your finances will allow and get outside and start developing those skills. Film has lower noise than any of them. Take it from me you don't want to do film.

Griz

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griz11

griz11

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Specs alone don't make great pictures. Skills and dark skies are much more important. And if you are anywhere close to being serious about all this a DSLR is a huge compromise at best. I'll spend my cash on a good mount use the camera I have and if I get good enough to warrant worrying about electrons I'll get a cooled ccd and a telescope. No way I'd buy a DSLR specifically for astro. I bought the 7D2 to take motorsports pictures the fact that its Canon's best camera for astro is just icing on top. I am glad they have gotten to the point they take reasonable astro shots. Last time I was into this stuff the only way was film or cooled ccd. And the cooled ccds were pretty awful. On the noise front I'd be more interested in dark current as it rises with temp. Readout noise is fixed. Uncooled camera noise that rises with temp. The camera or you can remove the dark current level but not the noise from it. A good page on noise is here. https://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html  Quite a bit to chew on but lots of really good info. 

Griz

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kalasinman

kalasinman

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I'm just saying that the idea that Canons are better for astro is old news and contains many ideas that are no longer valid. If you don't want to believe the figures, your choice, but it doesn't change them. I believe it does a disservice to others to promote old ideas that are no longer valid in all cases. An example would be that more pixels are better.

One must take read noise as well as thermal noise into account. One must take longer exposures to get delicate data above the read noise, or it is hidden. Read noise readings below those of some CCDs ( with a patched D7000 or D5100, for example. Measured at 1.7e) means shorter exposures to obtain usable data.

If using a DSLR for astro is such a huge compromise, that would be true for both brands. I see many great astro imagers here and elsewhere use DSLRs either alone or with data from CCDs blended into one image.

As to sports photography, a trip to the track anywhere will reveal many pros using Nikon.

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wxsatuser

wxsatuser

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Bloomin 'eck I though I had wandered into a photography forum by mistake...

As Harry Hill would say  Canon v Nikon FIGHT!!! :evil::grin:

CvN%20fight.jpg

Get the most out of what you have got...  If at the end if it you feel you need to move on to improve then go for it...

Peter

The fight has already taken place. :grin:

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Psychobilly

Psychobilly

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I'm just saying that the idea that Canons are better for astro is old news and contains many ideas that are no longer valid. If you don't want to believe the figures, your choice, but it doesn't change them. I believe it does a disservice to others to promote old ideas that are no longer valid in all cases. An example would be that more pixels are better.

One must take read noise as well as thermal noise into account. One must take longer exposures to get delicate data above the read noise, or it is hidden. Read noise readings below those of some CCDs ( with a patched D7000 or D5100, for example. Measured at 1.7e) means shorter exposures to obtain usable data.

If using a DSLR for astro is such a huge compromise, that would be true for both brands. I see many great astro imagers here and elsewhere use DSLRs either alone or with data from CCDs blended into one image.

As to sports photography, a trip to the track anywhere will reveal many pros using Nikon.

Indeed DSLR's even the manufactures "special" are a compromise...

But it's one I am more than happy to make as I normally shoot a couple of thousand frames a week under variable weather conditions with my 5DIII and 7D II...

Having already seen images from grizII's "standard"  7DII both astro and "action" I eagerly await some from your hacked 5100....

As my sig Indicates I have and use both Canon and Nikon although the Nikons older generation and was dire for astro and finally got retired from macro duty last year... 

Peter...

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Psychobilly

Psychobilly

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Being a Canon man I'd save my pennies for a 5DS-R , same spec as the new 5DS but with the low-pass filter already removed .... :laugh:

 50.6 Mp large RAW frames will make for some hefty TIFF files though ...  :p

Tempting isn't it.... :evil::grin:

Same advanced AF as the 7D II in a full frame sensor....

It will be interesting to see how low light performance compares to the 5DIII I expect it to be closer to the 7DII - When the lights bad I still use the 5DIII over the 7DII...

Peter...

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kalasinman

kalasinman

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Indeed DSLR's even the manufactures "special" are a compromise...

But it's one I am more than happy to make as I normally shoot a couple of thousand frames a week under variable weather conditions with my 5DIII and 7D II...

Having already seen images from grizII's "standard"  7DII both astro and "action" I eagerly await some from your hacked 5100....

As my sig Indicates I have and use both Canon and Nikon although the Nikons older generation and was dire for astro and finally got retired from macro duty last year... 

Peter...

As far as my future Images go, I make no claim to being the poster child for Nikon or the patch. Giving someone a strad. doesn't mean they can play it. I've been taking sky pictures since May of last year. What I AM saying, is that revolutionary work has been done and deserves a look.

This isn't about older generation Nikons. This is about new technology, unavailable previously. I wouldn't be silly enough to try to start fan fight in a Canon crowd.

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Psychobilly

Psychobilly

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As far as my future Images go, I make no claim to being the poster child for Nikon or the patch. Giving someone a strad. doesn't mean they can play it. I've been taking sky pictures since May of last year. What I AM saying, is that revolutionary work has been done and deserves a look.

This isn't about older generation Nikons. This is about new technology, unavailable previously. I wouldn't be silly enough to try to start fan fight in a Canon crowd.

It's an exciting journey and I am sure one you will enjoy.. plus your in the right place for plenty of help and advice... You recent acquisitions are pretty well thought out :)

Peter...

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Alien 13

Alien 13

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I hope the Nikon does well a little competition and the realisation that there is a viable market can only be a good thing for AP in general.

I wonder when the big boys start will start eating into the dedicated CCD market because at some point it will happen.

Alan  

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Alien 13

Alien 13

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Compared to the mainstream DSLR market it's still a small niche for them.... 

I wonder how many 7DII's (one of the most anticipated DSLR's of recent years) were pre-ordered...

Peter...

Perhaps, but I wonder how many skywatcher scopes are sold worldwide each one fitted with the dreaded T thread that becomes irrisistable at some point.

Alan

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